zfs discuss - Dec 2007 - zfs rollback without unmounting a file system

Hello zfs-discuss,

  http://bugs.opensolaris.org/view_bug.do?bug_id=6421210

1. App opens and creates an empty file /pool/fs1/file1
2. zfs snapshot pool/fs1 at 1
3. App writes something to file and still keeps it open
4. zfs rollback pool/fs1 at 1

Now what happens to fd App is using? What is a file contents from App
point of view as long as it''s still open?
New opens of that file will oen empy file I guess.


  

-- 
Best regards,
 Robert Milkowski                          mailto:rmilkowski at task.gda.pl
                                     http://milek.blogspot.com

Allowing a filesystem to be rolled back without unmounting it sounds unwise,
given the potentially confusing effect on any application with a file currently
open there.

And if a user can''t roll back their home directory filesystem, is that
so bad?  Presumably they can still access snapshot versions of individual files
or even entire directory sub-trees and copy them to their current state if they
want to - or whistle up someone else to perform a rollback of their home
directory if they really need to.

I''m not normally one to advocate protecting users from themselves, but
I do think that applications have some rights to believe that there are some
guarantees about stability as long as they have a file accessed (and that the
system should terminate that access if it can''t sustain those
guarantees).

- bill
 
 
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